This invention relates to a cylinder or reel type cutterhead that is used in a forage harvester to reduce crop material to a size suitable for feed purposes.
Forage harvesters for removing crop material from the field, reducing the crop material in size, and discharging the reduced crop into a collector vehicle are well known, and most currently marketed forage harvesters utilize a cylinder or reel type cutterhead, the crop material being fed over a stationary shear bar in a generally radial direction into the rotating cutterhead which chops the crop into appropriate particle sizes. A typical cutterhead would have approximately an 18-inch diameter and a 22-inch length and, a number of knives are mounted on the cutterhead periphery and extend the length of the cutterhead, the knives generally being helical in shape. Although the number of knives provided varies widely, most modern high-capacity machines generally provide at least six knives to provide a sufficiently fine cut.
A major problem in operation of forage harvesters has been cutterhead maintenance, both in the maintenance of the knife cutting edge and replacement of knives damaged by the ingestion of foreign material. The relatively long helical knives are both difficult and expensive to replace. In addition, most previous cutterheads have utilized a relatively expensive and complicated knife mounting structure, so that the cost for both new and replacement cutterheads have been relatively high. Replacement of the entire cutterhead is necessary in some cases when foreign material is ingested, the entire cutterhead disintegrating when a hard object of substantial size is fed into the cutterhead.
It is known to provide such a cylinder-type cutterhead with a series of relatively short knives, the knives being arranged in circumferential rows that are disposed adjacent to one another so that the knife cutting edges conjunctively generate a cylinder extending the length of the cutterhead. Such machines have primarily been marketed in Europe and are illustrated in European prior art. While the short knives of such machines are more readily and less expensively replaced than the long full-length knives, such knives still have had a relatively complicated and expensive mounting structure, and the individual knives, although short, have nevertheless been relatively complicated.